OBSERVATIONS ON EGGS OF EUBLEPHARID LIZARDS, WITH COMMENTS ON THE EVOLUTION OF THE GEKKONOIDEA by YEHUDAH L. WERNER Department of Zoology, The Hebrew University of Jerusalem, Jerusalem, Israel With one plate CONTENTS Abstract 211 Introduction 212 Methods 212 Observations and remarks Coleonyx variegatus variegatus (Baird) Observations 213 Remarks 213 Coleonyx variegatus bogerti Klauber Observations 214 Eublepharis macularius (Blyth) Observations 214 Remarks 214 Hemitheconyx caudicinctus (Duméril) Observations 215 Remarks 215 Aeluroscalabotes felineus (Günther) Observations 215 Remarks 216 Discussion Eggs of Eublepharidae 216 Status of the Eublepharidae 218 Evolutionary aspects 220 Conclusions 221 Dedication and acknowledgements 222 References 222 ABSTRACT Captive specimens of Coleonyx v. variegatus, C. v. bogerti, Eublepharis macularius and Hemitheconyx caudicinctus laid parchment-shelled, moisture dependent eggs, resembling those of diplodactyline geckos and most lepidosaurians. Eublepharid eggs, including those of Aeluroscalabotes measured in radiographs, are twice as long as broad. Supporting and complementary evidence in the literature is considered. It is concluded 212 ZOOLOGISCHE MEDEDELINGEN 47 (17) that the Eublepharidae are a monophyletic group of the Gekkonoidea, retaining the primitive egg type. Functional and evolutionary aspects of various characteristics of different gekkonoid eggs are discussed, and conclusions drawn. INTRODUCTION Geckos constitute the superfamily Gekkonoidea, comprising three families: Eublepharidae (5 genera), Sphaerodactylidae (5 genera) and Gekkonidae; the last named family includes two subfamilies, Diplodactylinae and Gekko- ninae (Underwood, 1954, 1955). The Diplodactylinae as recently redefined are restricted to Australasia (14 genera) while the nearly cosmopolitan Gek- koninae include the majority of geckos (some 50 genera) (Wermuth, 1965; Kluge, 1967; Bustard, 1968). Concerning the eggs, the whole superfamily Gekkonoidea has traditionally been regarded as characterized, among other things, by the brittle, hard-shelled eggs (Kluge, 1967 : 12; earlier references in Bustard, 1968). However, Shaw (1950 : 28) had already spoken of the "soft-shelled eggs of the gecko" Coleonyx variegatus variegatus. Actually, the geckos of the subfamily Diplodactylinae (sensu Kluge, 1967) lay pliable, parchment-shelled eggs similar to those of lizards and snakes in general. This is shown by the ample evidence provided and cited by Bustard (1965 : 298; 1967; 1968). The same has been suggested by Bustard (1967: 283; 1968 : 163) to apply also to the Eublepharidae, on the basis of his knowledge of the eggs of Coleonyx, and Minton's (1966 : 73) observations on eggs of Eublepharis. The purpose of this contribution is to bring together miscel­ laneous additional records on eublepharid eggs, some of which confirm Bustard's suggestion, and to discuss certain evolutionary implications. METHODS Unless otherwise acknowledged, casual observations were made on lizards kept for other work in the vivarium of the Auditory Research Laboratories, Princeton University, from October 1967 to October 1968. During most of that period the lizard room was automatically lighted for 12 h daily by fluorescent and infra-red lamps. All eublepharids were in terraria more than ι m from the infra-red lamps. Light and dark periods were coupled separately to thermostatic heating systems, but both the diurnal and the (lower) noc­ turnal temperatures varied seasonally, and to some extent between parts of the room. Prevalent temperature conditions will be described where pertinent. Food consisted of mealworms and, occasionally, grasshoppers obtained by grass-sweeping. Water in a small dish was always available. Eggs were measured with callipers and are described in terms of their length, their greatest breadth (occurring at half-length), and their ellipticity (ratio breadth to length, Preston & Preston, 1953). WERNER, EGGS OF EUBLEPHARID LIZARDS 213 OBSERVATIONS AND REMARES Coleonyx variegatus variegatus (Baird) Observations. — In 1966, Prof. H. Mendelssohn (Tel-Aviv University) presented me with two soft-shelled eggs, much like those of lacertids, laid by geckos which he had received from Dr. P. F. A. Maderson (then at the Uni• versity of California, Riverside). The eggs had been discovered in the terra• rium on II August 1966. I kept them between two sheets of moist cotton wool at (unrecorded) room temperature (in Jerusalem). One I opened on 23 August 1966. It contained a live advanced embryo, which I fixed in Boin's fluid (GK 427; after 2 years in alcohol: head and body, 28.5 mm; tail, 23.5 mm). The other hatched on 30 August 1966, carrying on its umbilicus a small remnant of yolk, and was fixed in formalin (GK 428; after 2 years in alcohol : head and body, 28 mm; tail, 21 mm). Prof. Mendelssohn informed me, that earlier clutches had been lost due to their drying up, because the staff had not expected that geckos would need a moist substratum for oviposition. Thereafter the sand was moistened. At Princeton, fourteen animals that had been collected by Prof. W. W. Mayhew and myself in the sand-dune country near Glamis, Imperial County, southern California, on 15 August 1967, were kept in terraria furnished with dry sand. Most of these animals were sacrificed for other work early in 1968. Three surviving pairs produced several eggs in the early summer of 1968. All were discovered too late in the dry sand, in a shrivelled condition, something which would never happen with the hard-shelled eggs of "typical geckos" (Gekkoninae). Hence more detailed data of these eggs are not available. Remarks. — Shaw (1967) summarized his ample experience in breeding these geckos in the San Diego Zoo. The laying season is from late May to mid-September. During this time, a female produces usually two and some• times three clutches, and one female produced four clutches in one season. A clutch consists of 1-3 (usually 2) eggs. The fresh eggs are very variable in size: length, 12.7-20.8 mm; width, 7.6-10.2 mm. This wide range is based on a rather large sample: nearly 100 clutches hatched. The shell is pliable, and size increases during incubation: length increased up to. 21.9% and width up to 37.1%. Incubation lasted 59-81 days at "temperatures of about 80o F" (26.5o C). Neonati average 32 mm in snout-vent length with a tail of 30.5 mm. Hence there is no doubt, that the parchment-like condition of the shell is normal in this species. Shaw's experiences are comparable to those usually made with lizard eggs. His observation of clutches containing three eggs is noteworthy and will be discussed later. 214 ZOOLOGISCHE MEDEDELINGEN 47 (17) Fitch (1970 : 11-12) cites additional sources on reproduction in Coleonyx, including a claim for clutches of 3-4 in Coleonyx elegans in Chiapas, Mexico (Alvarez del Toro, i960 : 74). Coleonyx variegatus bogerti Klauber Observations. — Several eggs were laid by animals purchased in the autumn of 1967 (from the "Pet Corral", Tucson, Arizona). The parchment- shelled eggs had been buried in the dry sand of the wooden terraria (by the females?), and were discovered in a dried and shrunken condition. Eublepharis macularius (Blyth) Observations. — Several pairs, all of which originated from West Pakistan (through various dealers) were kept at Princeton. Some of these had been obtained, half-grown, in 1963. Eggs were laid in the terraria repeatedly from 5 May 1968 (earliest oviposition) to 26 August 1968 (last oviposition). All eggs had pliable, parchment-like shells. Apparently clutches always contained one or (usually) two eggs. Each female must have produced two or three clutches in this time, and possibly more. Many of the eggs were discovered in the morning in a shrivelled, dried-up condition due to their pliable shell; they were usually laid, at night between 1700 and 0900 h (local time) and the sand was mostly dry. Efforts were made to incubate eleven eggs, arranged between moist sand and cotton wool, at a room temperature fluctuating daily between ca. 24 and 27-32^. All these attempts failed, due to mould or drying up, although some eggs survived for over forty days. During this time it sometimes happened that an egg started to dry up, developing an elongate 'dimple' parallel to its long axis. This could often be remedied by increasing the moisture of the covering cotton wool, or increasing the area of contact between the latter and the egg. The egg would imbibe water and resume its turgescence and shape. Eight eggs that were measured when 1-2 days old, ranged in length from 26.5 to 34.0 mm (mean 29.7 mm); their breadth was 13.5-17.0 (mean, 15.3) mm; and their ellipticity was 0.462-0.561 (mean, 0.516). Remarks. — The observations made by Minton (1966:73) similarly indicate a laying season from late April to mid-August. He observed a specific female laying three clutches with 3-4 week intervals. He already noted the pliable shell. The seven eggs he measured were 31-35 mm long and 13-16 mm broad. He, too, failed to have any eggs hatch, although some devel• oped for four weeks. A remarkable observation of Minton's is that on 11 September a captive female laid three eggs. Schifter (1967) likewise obtained from his captive pair eggs that failed WERNER, EGGS OF EUBLEPHARID LIZARDS 215 to hatch, and comments on the parchment-like shell. The two clutches were laid in mid-July and on 24 August 1966. Oviposition occurred late in the evening. Schifter describes the size as 25 X 10 mm; this relatively small size may be due to the limited age of his animals, which had been bought as juveniles in the preceding year. Hemitheconyx caudicinctus (Duméril) (plate 1, top fig.) Observations. — On 27 December 1967 I purchased (from "Noah's Ark", Princeton, New Jersey) two male and two female adults of this West African species. Together with the animals I received two eggs, which had been found in their cage. These were typical pliable-shelled squamate eggs, each 27 mm long, but so caved-in due to desiccation that the width could only be guessed at- One was discoloured, yellowish.